Sorry if this issue has been covered to death. This is a specific rear window issue.

On two recent trips my '93 4Runner covered 30+ miles of dusty, washboard, gravel roads in southern AZ & NM. When I arrived at my destination the rear window lowered fine. When I attempted to raise it w/ either console switch or rear key switch I got the alarm beep-beep-beep as if the tailgate was not properly closed. The rear wiper was properly seated. Big problem in the backcountry along the US-Mexico border w/ an unsecured truck. The trip out sucked, literally. TONS of dust sucked in which coated everything. An hour back on pavement and it works again! The same sequence of events on a later trip. The window worked fine on pavement. Twenty miles on washboard and it won't raise after being lowered. Back on pavement after a few hours and it works again! Vibration is clearly the culprit but tough problem to isolate & solve when it self-corrects. A friend w/ a 2nd gen 4Runner had someone bypass a "sensor" or circuit IN THE TAILGATE which corrected the same problem. I've had it checked out at a few local Toyota places and the relay is unlikely to be the source of the problem. Anyone know of a sensor or circuit in 2nd generation 4Runner tailgate that can be bypassed?